Study On The Preparation Of Corn Starch Film And Its Charactereristics

In21st century, people pay more attention to the environmental problems and the safety caused by food packages. Study on preparation of packing film based on natural polymers materials such as starch has wide application prospects. However, the existing starch packing film has poor mechanical properties and practicability, which limits the application in food packaging industry. Based on the problems of existing starch packing film, this paper mainly study on preparation and performance measurement of ordinary corn starch-based film, composite film which use starch and zein as ingredients, and four different treatments on the influence of the starch film. This study expects to provides theoretical and technical support to the development of multi-functional edible food packages. The main conclusions of this study are as follows:1. corn starch composited film:The cross structure of the corn starch chosen by this study was disappeared after gelatinization, and the temperature of which was measured at90℃around. This study chooses glass as carrier, and casting as film forming approaches. The drying temperature is at40～55℃, drying time is at4～6h. The appropriate concentration of the corn starch is60g/L. The starch film has the optimal mechanical performance when glycerin is chosen as the plasticizer, concentration of which is kept at18g/L. When the concentration of xylitol is15to18g/L, it could replace glycerin as plasticizer. In the high temperature conditions, glycerin performs higher thermal stability than xylitol, but both of them are more stable than the starch film with nothing. The starch film has the most balanced mechanical performance when the mixture of glucomannan and chitosan (1:1) is chosen as reinforcer, concentration of which is kept at1.8g/L. When the proportion changes, the plasticity and intensity also changes.2. Starch-zein composited film: The protein content is8.238g/100g in this study, accounts for about8.2%of maize flour. The zein content is4.822g/100g before decoloring, accounts for about4.8%of maize flour, accounting for59.5%of the corn protein. When the ratio of activated carbon to zein reaches1:8, it performs the excellent effect of decolorization, and the recovery rate of zein reaches90%. When60g/L corn starch,15%volume ratio of zein solution,12g/L glycerin is added, starch-zein composite films has optimal moisture resistance, solubility is only44.2%. In40-80℃, composite film posses excellent stability and lower heat loss.3. Effect of treatments on starch film properties:The film posses excellent mechanical properties, which is treated by high microwave processing temperature for4minutes. The tensile strength comes to29.3MPa, which has increased24.5%point than the ordinary corn starch film and the thermal stability is also higher. Using600W ultrasonic processing for10minutes, the starch film posses excellent mechanical performance and thermal stability. Tensile strength comes to28.35MPa, which has increased20.35%point than the ordinary corn starch film., but film sex differences. The stearic acid esterification starch, membrane water resistance was up14.39%, but heat stability is poor, not a good film. In the actual application of ultrasonic conditions can consider to microwave or deal with the starch film. The moisture resistance of malate corn starch-based films increases by9.35%, and the melting temperature increases by10℃. However, the film-forming property is poor. Likewise, the moisture resistance of stearate corn starch-based films increases by14.39%, which is also very poor in film-forming property and thermostability.The study indicates that the plasticity and mechanical properties of corn starch film could be significantly improved by adding plasticizers, Reinforcer or zein or using different treatments.